Two of the contacts are for the cruise control, and they should have a complete circuit when the pedal is not depressed. I don't recall which set is which, but obviously they will not be connected at the same time.

 

To all - I have determined the issue with the Brake lights on my 2000 Jaguar Vanden Plas XJ8 - the issue is the Brake Petal Switch but I thought it would be helpful to others on how to know it is the switch vs. the Security Locking Module Unit also called SLCM

First of all if NONE of the brake lights work - the 2 tail lights and the single light in the rear window - it points to the brake switch at the petal. If you get the rear window light working but not the 2 tail lights it will point to the SLMU as the tail lights are on their own circuit vs the rear window light.

When checking the switch there is 4 terminals in the switch (see pic 3) check terminals 1 and 4 - this controls the brake lights - terminals 2 and 3 controls the cruise control (stoping it when you hit the brake)

Now if you want to see if it JUST your brake switch and not the SLMU (also called SLCM) controller in the back you can manually jump the plug that goes into the brake switch by running a wire from the 1st hole in the plug to the 4th hole in the plug (see pic 4 - last pic) - make sure you really, really push that wire into each hole - needs to be in there deep to make the connections. Once this is done, if your brake lights come on - all 3, then your controller is good and it is ONLY the switch you need to deal with. If you get only the rear window brake light coming on but not the 2 tail lights then you will have to look at replacing your controller also if both the switch and controller is having issues.

I hope all of this helps anyone in the future with a similar issue:
Dave Mc

Picture 1 - Brake Petal Switch from '00 Jaguar Vanden Plas XJ8

Picture 2 - Brake Petal Switch from '00 Jaguar Vanden Plas XJ8 - other side view

Picture 3 - Brake Petal Switch from '00 Jaguar Vanden Plas XJ8 - this view shows the plug on the switch itself with what the various terminals are responsible for controling

Picture 4 - Brake Petal Switch from '00 Jaguar Vanden Plas XJ8 - pic is of the plug that GOES INTO the brake petal switch and how to jump it to maually turn on your brake lights.

 

Good job doping it out correctly: when my brake lights went out (SLCM issue), the high brake lights worked (for a while I ran a parallel line to the rear left (rear rights worked). New SLCM worked for me. Another check would be to see if cruise control came on (or out on application of brake).

 

Just a VERY important side note - when I got the NEW switch - see the pictures I posted in this post. As I stated, Terminals 1 & 4 in the plug control the Brake Lights. When you test with an OHM meter these 2 terminals they are active UNLESS the switch is depressed. Once depressed the switch turns off - so for the brake lights, the switch is ON - OHM meter reads flow when not depressed and OFF when depressed OHM meter shows no flow. For terminals 2 & 3 the center 2 it is just the opposite for the cruise control. Hope this clarification helps.